12AT7

A Westinghouse JG-12AT7 premium military tube. Notice the green paint on top.

Modern Russian made Mullard and Genalex brand 12AT7s. There is nothing "Mullard" or "Genalex" about them, except the names. Mullard stopped making vacuum tubes in 1982. Genalex ceased production in 1988. These are both made by New Sensor Corporation at a facility in Saratov, Russia.   An Electro-Harmonix 12AT7. This is the "house brand" of New Sensor Corp.      An American and a New Sensor Tung-Sol 12AT7. The Russian tube is larger but the pins are thinner. New Sensor acquired the Tung-Sol name in May of 2002. I get the feeling that every brand of 12AT7 made by New Sensor is the same tube with a different logo. It is interesting that the Russian tube is labeled both 12AT7W and 6201, because you don't normally see these together. They designate a higher quality ruggedized military version of the tube, used in mobile, aircraft and missile applications. The 6201 is resistant to impacts, acceleration, vibration, drastic changes in temperature and cycling on and off. Do you think the Russian 6201 conforms to this standard? I bought one of each to find out. I didn't drop the Russian tube, bang on it 80 times in four different positions, swing it around at 2.5 times the force of gravity, put it in the freezer while it was hot, put it in the toaster oven while it was frozen, or shake it 25 times a second for 32 hours (per the 6201 data sheet), but I did test it.     The first triode had a mutual conductance of 4000 micromhos, which is perfect. The second triode tested at 2400. I sent it back and asked for a tested tube as a replacement. Both triodes of the replacement tested about 3400. The American Tung-Sol tested 4200 / 3900. Tube  Price  Triode 1  Triode 2  Gain  Tung-Sol 12AT7  $20.00  4200  3900  63/58.5 New Sensor 12AT7W  $31.99 3400  3400  51/51 ?  When questioning the poor test results, a link in the reply pointed to a spec sheet put out by New Sensor Corp. It states the amplification factor, or gain, of the tube is 45. (An actual 12AT7 has a gain of 60.) It doesn't show what the tube test results should be, and because the spec sheet doesn't list the plate resistance you can't calculate the gain to verify it's really 45. Additionally, the tube is physically larger than a vintage 12AT7, and the dimensions on the spec sheet are incorrect. It seems they made up their own specifications and called it a "reissue," but it's not a 6201 or even a regular 12AT7. For $31.99 you can do a lot better. A new old stock RCA 12AT7 is about half the price of a miserable Russian "reissue." These three New Sensor Corp. spec sheets don't agree with each other, though they are all 12AT7s made by the same company. The New Sensor Tung-Sol spec sheet is here. The Electro-Harmonix 12AT7 spec sheet is here. The New Sensor Mullard spec sheet is here. For comparison, the General Electric spec sheet is here. Data sheets from various manufacturers of actual 12AT7s are here.     Gold plated pins! On the left is a used, vintage Amperex 12AT7 with gold plated pins. On the right is a Russian Genalex, also with gold plated pins. Just plugging the Russian tube into a socket scraped off the gold. It looks more like gold paint. Whatever the gold colored substance is on the Russian tube, it's probably useless. (Pictures from ebay)   Radio Shack Realistic "Lifetime" brand tubes also had gold plated pins. "Lifetime" tubes cost more, but were "guaranteed for life." For example, in 1970 a 12AT7 from Lafayette was $1.44. A Radio Shack "Lifetime" tube was $2.19, but if it went bad you got a replacement for free. That sounds like a good deal, but the guarantee didn't mean Radio Shack would replace the tube forever. The length of the guarantee wasn't for the length of YOUR life, and if the tube went bad, it's life was over. So whose life was it guaranteed for?     The "lifetime" was the "life of the apparatus in which it is used." Radio Shack began to offer "Lifetime" tubes in 1965 when radios and televisions that used vacuum tubes were becoming obsolete. Many of these tubes weren't in service long enough to go bad, so it was a good deal - for Radio Shack. The salesman would spot you testing your tubes, and instead of coming home with a new tube for your old radio, you came home with a brand new transistorized AM/FM cassette player. By the way, $2.19 in 1970 is $17.81 in 2025.

Back in the day when tube counterfeiting was a big business (it still goes on today) you'd take an American made tube and rebrand it as a British Mullard or German Telefunkin, but never the other way around. Nobody ever rubbed off the Mullard label and stamped "Philco" on it. I find this rather amusing.

New "vintage" Mullard tube boxes. Available on ebay. Be careful when you buy a 12AT7. A $7 tube can be turned into a $70 tube with a damp rag, a rubber stamp, and a Mullard box. You can purchase boxes for almost every major brand.

I visited the Ali Express website and bought a Chinese PSVANE brand labeled ECC81 (the European designation of a 12AT7). Like the Russian tube, the diameter is larger than a vintage 12AT7. (Coincidence?) The price was $13.74. Was that a good price? You can buy a new old stock General Electric 12AT7 for less. The box is a little too "elegant" for my liking. I think it looks like a personal care product came in it. "Honey, I've got that rash again. Can you get me the Pissvane from the medicine cabinet?"

There is an unusual structure inside the tube. It holds up a post that has the getter ring attached to it. I went back to Ali Express to see what I had ordered, and none of their ECC81 tubes had this thing in the pictures.

Picture from Ali Express. The odd structure holding the getter is not inside the tube. Dang, none of my pictures turn out this good. How do they do it?

Now for the test! Both triodes of a new 12AT7 should read at least 4000 on the middle scale of this meter. One triode of the PSVANE tube read 2800 and the other one gave a reading of 3100, which is worse than its Russian counterpart. A 12AT7 should read 3800 after 500 hours of use at the maximum plate voltage of 250 volts. This new one from China seems like it's been in use for a thousand hours already. PSVANE must be selling the rejects of their "premium" versions. Fortune cookie say, "Gullible man buy cheap tube." PSVANE also makes a version that they sell for over $100. Do you want to take a chance on it? Not me!

Like New Sensor, the PSVANE data sheet does not tell you what the test results should be. From looking at reviews on Amazon and my own experience, I've found you're liable to get a junk, mis-matched tube in the mail. If you complain, they send you a better one. I purchased the Russian Tung-Sol 12AT7W/ 6201 from an online tube store via Amazon. When I found how bad it was, I returned it for a replacement. The seller sent the replacement but told me I had sent him back a tube that was ten years old. He was going to charge my credit card for two tubes. It seemed to me he was a scammer, and thought he'd get a double payment for his POS vacuum tube. It's even possible the first tube he mailed and got back was actually ten years old. Eventually things were resolved, the first tube was refunded and I kept the second tube. I didn't return the Chinese PSVANE, because I purchased it EXPECTING it to be bad.

Tube  Price  Triode 1  Triode 2  Gain  Tung-Sol 12AT7  $20.00  4200  3900  63/58.5 New Sensor 12AT7W  $31.99 3400  3400  51/51 ?  PSVANE 12AT7 $13.74 2800 3100 42/46.5 ?

Why is the 12AT7 still being made today in Russia and China? Why would you want a new one? Of what use today is a vacuum tube designed in the 1940s for television sets? It would take FIVE BILLION of them to make a CPU used in a typical smart phone or home computer. They are used in guitar amplifiers! They work fine at audio frequencies and are listed online as "preamp vacuum tubes." People who play guitars have driven up the price of vintage 12AT7s to the point where it became profitable to manufacture new ones, and the demand is over one million per year. Tube sellers extol the virtues of various brands when used in guitar amplifiers. One site states, "If you are looking for clarity and headroom go for grey plates, if you would like more warmth and a richer overdrive sound go with black plates!" The color of the plates makes no difference whatsoever. "Headroom" is a lack of distortion and "overdrive sound" IS distortion. These characteristics are obtained with the circuitry and controls in the amplifier, not by changing tubes that have different colors inside. What people are actually hearing when swapping tubes is the differences in the poor quality Russian and Chinese tubes.

12AT7 vacuum tubes in a modern McIntosh tube amplifier, illuminated from below with green LEDs. They are labeled "McIntosh USA" but they were manufactured in Slovakia, Russia. McIntosh Laboratory is not named "McIntosh USA," yet that's how the tubes are labeled. Is this a marketing stunt? In response to an email questioning this, a McIntosh tech wrote that the tubes were made by JJ Electronic but didn't explain why they were labeled "USA." A second email went unanswered. The amplifier in this photo (McIntosh MC1502) lists for as much as $14,000, but they won't answer a simple question about the vacuum tubes. Nice!

Since JJ tubes are used in such expensive amplifiers, let's test one! Here's a brand new JJ.

3000 and 3100 micromhos. Marginally better than the cheap PSVANE.

Tube  Price  Triode 1  Triode 2  Gain  Tung-Sol 12AT7  $20.00  4200  3900  63/58.5 New Sensor 12AT7W  $31.99 3400  3400  51/51 ?  PSVANE 12AT7 $13.74 2800 3100 42/46.5 ? JJ Electronic 12AT7  $18.95  3000  3100  45/46.5 ?

THE TAKEAWAY: The 12AT7 has de-evolved from a radio frequency amplifier and oscillator (up to 300 megahertz) with an amplification factor of 60, to an audio frequency amplifier with an amplification factor of 45. The "re-issues" will work poorly in antique equipment and are now marketed for modern audio amplifiers. Though a logical evolution of its use due to obsolescence of the equipment it was originally designed for, the new lower specifications should have resulted in a new tube designation. This could be the case with the 12AT7EH, but the EH stands for "Electro-Harmonix," not a new version of the 12AT7. The two triodes of a new tube should match in performance. A convenient but imprecise way to evaluate a modern 12AT7 is to swap it with a working one and note the difference in audio output. In the past, if a more accurate test was wanted, drug stores, hardware stores and electronics shops had tubes testers, but these machines disappeared decades ago. Knowing that a newly purchased tube may never be tested by the user, a seller might supply a tube (by mail) that is marginally performing, with triodes that are mis-matched and out of spec. Tube sellers use the color and length of the plates as well as the shape of the getter support structure as a sales pitch, making various nonsense claims based on these characteristics. Foreign tube manufacturers have purchased American and European brand names and deceptively market their tubes under these names, along with the designations 12AT7 and 6201. Modern spec sheets omit specifications, state incorrect specifications, and lower the specifications to make the spec sheet match the tube. Missing data makes it difficult to calculate the tubes actual amplification factor. Modern 12AT7s are, however, acceptable for use in musical instrument amplifiers.

When I need to buy a 12AT7 for my radio I want reparations from guitar players, and I want Steve Hackett to deliver the check so I can get a picture of us together so it looks like I'm his friend or something.

Like this, but the picture won't be fuzzy and instead of a CD it will be a check made out to me. Photo taken at the Sellersville Theater, Sellersville, PA